DKK1 and colorectal cancer: Among these genes, they found that dickkopf WNT signaling pathway inhibitor 1 (DKK1), an important inhibitor of the Wnt pathway, was significantly overexpressed in EYA4-overexpressing colorectal cancer cells; therefore, they speculated that EYA4 could act as a tumor suppressor gene and inhibit the Wnt signal pathway in colorectal cancer cells by up-regulating DKK1 [20].